This guy makes an MX5 rollbar with "ANTIFLEX DOOR BARS, PROVEN TO ELIMINATE CHASSIS FLEX IN THE DOOR APPERTURE AREA OF YOUR MX5 CHASSIS, THUS GIVING MORE STABILITY WHEN CORNERING - COMBINED WITH OUR ROLL BAR, THIS GIVES THE REAR OF THE CHASSIS MORE RIGIDITY" and allows full seat back position thst others fall foul of. Something to consider. It will need to look purpose built an aggressive too.
it is possible for us to make a X19 style section that stores in the back. We can do that for a small extra charge and use the existing moulds with a removable stop inside to form a return flange (90 degress to the roof line). So with a Spyder with a fly screen and a version with the original screen with a soft top and there you have a complete range.